Reaction product of polyoxyethylene derivative of a fatty acid partial ester of hexitol anhydride and citric acid and an antioxidant containing the same



United States Patent 'Ofi 2,761,784 Patented Sept. 4, 1956 See Lloyd A. Hall, Chicago, 11]., assignor to The Griffith Laboratories, Inc., a corporation of Illinois Application November 6, 1952, Serial No. 319,177

9 Claims. (Cl. 99-163) This invention relates to reaction products of polyoxyethylene derivatives of fatty acid partial esters of hexitol anhydrides and citric acid and also to antioxidant compositions containing the same.

The protection of fats against oxidation has long been a problem. Lard, particularly, requires the presence of an antioxidant to avoid rancidity. These antioxidants must be fat soluble in themselves or made so. The antioxidants now primarily in use are. propyl gallate, BHA (butylated hydroxyanisole) and NDGA (nordihydroguaiaretic acid). In connection with all of these antioxidants, it has been customary to use synergists. Of these, citric acid is the most important because it not only improves the action of the antioxidant, but because it is a metal sequestering agent and thus prevents or inh-ibits color changes and also by its sequestration is in a position to remove metals which may act as pro-oxidants. Citric acid, however, is not fat soluble and the problem of obtaining proper distribution of it in the fatty material has not hitherto been overcome.

I have now discovered that citric acid may be rendered fat soluble as well as emulsifiable in water without in any way destroying the value of the citric acid as a synergist or as a metal sequestering material by reacting it under proper conditions with polyoxyethylene derivatives of fatty acid partial esters of 'hexitol anhydrides. When so reacted, it may be introduced to the fat in any suitable manner, either together with or separately from the primary antioxidant.

The polyoxyethylene derivatives of fatty acid partial esters of hexitol anhydrides are emulsifying or dispersing agents. However, inthe present case, they form a reatcion product of unknown chemical constitution with citric acid. The existence of this chemical product has been shown definitely by X-ray analysis. Micro-analysis of the reaction product shows a complete absence of citric acid. I

The preferred polyoxyethylene derivatives of fatty acid partial esters of hexitol anhydrides actually employed are a sorbitan trioleate polyoxyalkylene derivative and a sorbitan tristearate polyoxyalkylene derivative. Both of these compounds form an oil liquid at about 25 C. and tend to gel on standing. Their viscosity cp. at 25 C. is about 200 to 400. These compounds are partial esters of such common fatty acids as lauryl, palmitic, stearic and oleic acids and hexitol anhydrides such as hexitans and hexides, derived from sorbitol with polyoxyethylene chains added to the nonesterified hydroxyls.

In preparing a reaction product of this invention, sorbitan tristearate polyoxyalkylene derivative was added to corn oil previously heated to a temperature of from 245 to 250" F. and the heated solution agitated continuously for a period of 20 minutes. The temperature of the solution was gradually increased to about 265 F. following which anhydrous citric acid was added uniformly over the entire surface taking approximately 20 minutes for this addition. The temperature of 265 F. was maintained and the resulting solution stirred until No Drawing.

Md complete reaction occurred, following which ropyl gallate was then added. In those formulations in which BHA (butylated hydroxyanisole) was added, the solution was then cooled to about F. an'clBHA concentrate then added slowly. The resulting solution was stirred for about 25 minutes and then cooled.

Formulations were made as follows:

Percent Sorbitan tristearate polyoxyalkylene derivate 20.0 Anhydrous citric a 9.0 Propyl gallate 3.0 Corn oil 34.7

66.7 Sorbitan tristearate polyoxyalkylene derivative 20.0 Anhydrous citric acid 8.0 Propyl alla 6.0 Corn oil 32.7

66.7 Sorbitan tristearate polyoxyalkylene derivative 20.0 Anhydrous citric acid 4.7 Propyl gallate 8.0 Corn oil 34.0

1 66.7 sorbitan tristearate polyoxyalkylene derivative 20.0 Anhydrous citric acid.-. 4.0 Propyl gallate 9.0 Corn oil 33.7

Products A, B, C or D 66.7 BHA concentrate 33.3

BHA concentrate:

Butylated hydroxyanisole 13.32 Corn oil 19.98

Formulations were made with sorbitan trioleate polyoxyalkylene derivative as follows:

tr") I Sd'rbitan trioleatepolyoxyalkylene derivatives"; 23.000

' *A-hhydrous citric acidwceou 3.735 Propyl gallate 3.335 car's oil; 36.630 66.7

6* Products. B", D", E, or FI' I '66.7 BHA concentrate 33.3

I I 100.0 BHA concentrate: I

Butyl'a'ted hydroxyanisjcl'eg s- 1 3.32 Corn oil-.. "19:98

stead, thelines were different in character, thus indicating that newcompounds were formed. I i

it was found that the '8 to 6 ratio (formulation B above) of citric acid to propyl gallate results in a highly viscous product and appears bobe the limit of concentration of citric acid and propyl gallate. When the concen I that formulation :D apparently represents the limit of the polyoxyethylene derivatives of fatty acid partial esters o'f rhexitol'anhydrides -mitric acid :r'eaction produdts are synergist aird ioh seeuesreri'nga enm roe a'ntioziitlants gencar-ally. I MI The foregoing detailed gdescription isgiven for clearness of unclerstanding'only and no unnecessary limitations should be understeod the'refrom, as rhodifications will be obvious to those skilledin the art.

lclaim: I I I 1. As a new compound, the reaction .product of a po'lyoxyethylenc derivative of a fatty acid partial .ester of a hexitol anhydride and-citriclacid.

'2. A compound :asfset iiorlth in claim 1 in which .the

-polyoxyethylene derivative .is' .a rsorbitan tristearate poly- Ioxyalkylene derivative.

'3. AICQIIIPOSIUOB as -set forthinclaim 1 inwhich the -'polyonyethylene{derivative is. a sorbitan triolea'te .poly- :When employing sorbitan trisiearate polyoxyalkylenc derivative itwas found that optimum solubilization of the derivative in corn oil 'occ'urre'd'at a temperature ranging from 245 to"250 'F.-'whereas opt1n'1um solubllizaantiokiadntl I I I 6. A composition .as setffonthin .clairn5 in Which the' ;gallate.. I

tion' of -sorbitan trioleate*polyoxyalkylene derivative in co'rn oil "occurred at a temperature of from .201) as The same products may be prepared with cottonseed o'ilas well as other vegetable or animal oils. Selection of an animal oil as against selection of a vegetable oil will normally --be determined by-the 'product in whichthe rn'aterial is to be employed.

To prevent separation of the citric acid, it is important th'atthe amount of free water present during the reaction should not exceed about 2%. t I Instead of employing-anhydrous citri'c' acid in the above described formulations, -U. =-S.-P. crystalline citric acid (the monohydrate CsHaO7.HzO containing 8.58% H2O ofcrystallization) may be employed.

X-ray analyses of "the resultant 'antioxid'ant products of the above described formulations show that't'lte characteristic diffraction lines for citric acid as such were not present in the X-ray patterns for these products. In-

' a'iitioiii'dant comprisesipr py oxyalkilene derivative.

4. An .arit'ioi antccomp comprisinga solution in an oil .the fat :sohible reaction product of a ,polyoxyethylene-de native t of alfatt'y acidapa'rtial ester of a hexitolianhydridefland citric acid;

'5. An antio xidant composition comprising a solution in anedible iof the'iat asoluhle reaction .product-of a pjolyoiiyethylene derivative tier a fatty acid l partial ester er. a hejxitol afihydi'i detarid Icitricfacid and i an oil fsolubl'e 7; Alcolr t p'osiion-astsefifofthin claim S in which the ai-itioxijd ant: compriseslhutylated .hydroxyanisole. "8, The: Ehrtliod'fivhich comprises reacting a .polyoxyethylene derivative eri a .fatt'y acidipartial ester of .a hexitol anhydride vvith citric acid tofform a fatsolublesreactionp'roduct.

9. 1A compos'itionas set forth in claim-5 :in which the antioxidant comprises .,propy1 gallate and -butylated hydroXyani sole.

Whilst nave' iven erampieser particular iantiojiiidants, 

1. AS A NEW COMPOUND, THE REACTION PRODUCT OF A POLYOXYETHLENE DERIVATIVE OF A FATTY ACID PARTIAL ESTER OF A HEXITOL ANHYDRIDE AND CITRIC ACID. 